In addition to these great blessings and this great eminence which Allaah has given to mankind, He also gave them the blessing of intellect which raises them to the level of taking on responsibilities given by Allaah, and it also enables them to achieve and comprehend them. He also provided them with natural inclination to the truth which agrees with that which the Messengers of Allaah, 'alayhimus-salaatu was-salaam, came with: the noble revelation and the true religion which Allaah prescribed, and laid down as the way to be followed for mankind upon the tongues of His noble Messengers, may Allaah's praises and blessings of peace be upon them all. Allaah, the Most High, says,
"So set your face straight upon the true religion, firmly upon His religion and obedience to Him, the true religion of Islamic monotheism upon which He created mankind.  There is to be no change to the religion of Allaah. That is the true religion, yet most people do not know." 
Allaah's Messenger (صلى الله علیه وسلم) said,
"There is no child born except that it is born upon the fitrah, then its parents cause it to become a Jew, or a Christian or a Magian. Just as an animal gives birth to perfect offspring, do you find them mutilated?" 
'Iyaad ibn Himaar al-Mujaashi'ee, radiyallaahu 'anhu, said that the Prophet (صلى الله علیه وسلم) gave a khutbah one day and said in his khutbah,
"Indeed my Lord, the Mighty and Majestic, ordered me to teach you that which you do not know, from that which he taught me this day, 'The wealth which I confer upon My servants is lawful for them, and I created my servants upon the true religion, but the devils came to them and turned them away from their true religion, and forbade for them that which I made lawful for them, and ordered them to associate in worship with Me that for which I sent down no authority..." 
 Al-Fitr means to bring and create, and al-fitrah is the condition resulting from it. The meaning is that mankind was born upon a disposition and nature which is ready to accept the true religion. So if he were to be left upon that he would continue upon it, but those who deviate from it do so due to following human weaknesses and blindly following others... (an-Nihaayah of Ibnul-Atheer 3/457). Al-Haafidh Ibn Hajr, rahimahullaah, said in al-Fath (3/248),
"The people differ concerning what is meant by al-Fitrah and the most famous saying is that what is meant by the Fitrah is Islaam."
Ibn 'Abdul-Barr said,
"That is what was well-known with most of the salaf (predecessors), and the scholars of explanation (of the Qur'aan) are agreed that what is meant by the saying of Allaah, the Most High, ...'the true religion of Islamic monotheism upon which He created mankind...' is Islaam."
 Soorah Room (30):30.
 Reported by Bukhaaree (Eng. trans. 2/247/nos. 440, 441) and Muslim (Eng. trans. 4/1398/no.6423) and in a wording reported by Bukhaaree (Eng. trans. 2/262 no.476), Ahmad, Maalik in al-Muwatta and Tirmidhee, "Every child is born upon the Fitrah..."
 Reported by Muslim (Eng. trans. 4/1488 no.6853).